Skewed core matrix

ABSTRACT

A magnetic core memory of the type that has ring-shaped cores arranged in columns and rows and strung with wires along the axes of the columns and rows, wherein the axes of the columns are oriented at an angle of less than 90* with respect to the axes of the rows to thereby increase the width of the &#39;&#39;&#39;&#39;stringing window&#39;&#39;&#39;&#39; so that wires can be more easily strung through the cores. A preferred array has column axes oriented at approximately 77* from the row axes.

United States Patent Boice et al.

[ Mar. 18, 1975 SKEWED CORE MATRIX inventors: Michael F. Boice,Torrance; Niels Krag, Pacific Palisades, both of Calif.

Electronics Memories & Magnetics Corporation, Hawthorne, Calif.

Filed: Dec. 13, 1973 Appl. No.: 424,296

Assignee:

Us c1. 340/174 M, 29/604 1111. c1 011C 5/02, G110 11/06 Field of Search340/174 M, 174 MA; 29/ 04 References Cited UNITED STATES PATENTS H1966Gutwinetal..... ..340/174MA 1/1973 Sell et al. 340/174 M FOREIGN PATENTSOR APPLICATIONS 275,140 0/1970 U.S.S.R. 340/174 M Primary Examiner-JamesW. Moffitt Attorney, Agent, or F irm Lindenberg, Freilich, WasserinanRos en & Fernandez 57 ABSTRACT A magnetic core memory of the type thathas ringshaped cores arranged in columns and rows and strung with wiresalong the axes of the columns and rows,

wherein the axes of the columns are oriented at an angle of less than 90with respect. to the axes of the rows to thereby increase the width ofthe stringing window so that wires can be more easily strung through thecores. A preferred array has column axes oriented at approximately 77from the row axes.

4 Claims, 6 Drawing Figures SKEWED CORE MATRIX BACKGROUND OF THEINVENTION This invention relates to magnetic core arrays, and moreparticularly to an arrangement of the cores in such arrays.

Magnetic core memories commonly utilize large numbers of ring-shapedcores arranged in rectangular arrays and strung with wires along theaxes of the rows and columns. High capacity memories of small size andcost are produced by utilizing large numbers of very small cores, atypical memory section including many thousands of cores arranged on asubstrate. The use of small cores gives rise to problems in stringingwires through them. Some of the smaller cores may have an outsidediameter such as 14 mils (thousandths of an inch), a hole diameter of 8mils, and a thickness of 4 mils. With such a core oriented at 45 to therow and column axes, the stringing window or opening as viewed alongeither axis, may be less than threethousandths inch. Such a smallstringing window hampers the stringing of wires through the cores,inasmuch as the smallest available and practical needles utilized toproject wires through cores are'three-thousandths inch in diameter.Needles smaller than this are hard to procure and furthermore theybecome damaged very easily. Also, two wires are often strung along thecolumn axes, and it is often desirable to utilize large gauge wires, sothat a large stringing window along at least one axis is very desirable.The problem of stringing the wires and accommodating large gauge wiresis further compounded in the case of certain cores which are unusuallythick. A core array design which enlarged the stringing window tofacilitate the stringing of wires and to permit the accommodation oflarger diameter wires,

would facilitate the production of high density core arrays.

SUMMARY OF THE INVENTION on a substrate, in substantially straight rowsand columns, and with wires extending through the cores along the axesof the rows and columns. The axes of the columns are oriented at anangle of less than 90 to the axes of the rows in order to enlarge thestringing window along the axes of the columns, so that the column wiresare more easily projected through the cores and so that larger diameterwires can be utilized.

In one core array, the cores are oriented at slightly more than theconventional 45 to the row axes to slightly widen the stringing windowalong the row axes, eventhough this slightly decreases the stringingwindow along the column axes. However, the column axes are oriented atapproximately 77 to the row axes, instead of the conventional 90. Thisresults in a very large increase in the stringing window along thecolumn axes, so that large diameter wires can be strung therealong toincrease the speed of the memory. The use of an angle of approximately77 results in only a moderate increase of the core spacing and overallarray size, while providing a very large increase in the size of thestringing window along the column axes.

best be understood from the following description when read inconjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial perspective view of amagnetic core memory constructed in accordance with the invention; FIG.2 is a plan view of a portion of the array of FIG.

FIG. 3 is a greatly enlarged partial sectional top view of another arrayconstructed in accordance with the invention, wherein a thick core isutilized;

FIG. 4 is a plan view of the entire array of FIG. 1;

FIG. 5 is a greatly enlarged partial sectional top view showing one coreof the array of FIG. 2; and

FIG. 6 is a plan view of a portion of an array constructed in accordancewith another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a magneticcore memory 10 which includes a support or substrate 12 of insulativematerial with an array 14 of ring-shaped magnetic core 16 positioned onthe substrate. A group of row wires 18 extends through the cores alongthe row axes 20, while a group of column wires 22 extend through thecores along the column axes 24. FIG. 2 illustrates the orientation ofthe cores as seen in a plan view. In a conventional core array, the axesof the columns and. rows are oriented at to one another so that the rowand column wires extend at 90 (although an additional wire may beutilized which may extend at 45 to the row and column axes). However, inaccordance with the present invention, the row and column axes 20, 24are oriented at an angle C which is less than 90 and more than 45.

The memory 10 is constructed by first mounting the cores on thesubstrate 12, and then stringing wires through the cores. One row wire18'may be strung through each row of cores, and then one or two columnwires may be strung through each column of cores. Both stringingprocesses are difficult, but the stringing of the column wires may beespecially difficultbecause the holes of the cores are already partiallyoccupied by the row wires. The stringing is typically accomplished bywelding the front end of each wire to the rear end of a needle andprojecting the needle through the row or column of cores, so that theneedle can then be pulled to draw the wire through the cores. Thestringing window or width of the path along which the needle must moveis typically very small. FIG. 2shows the width W, along the rowdirection and the width W along the column direction. The cores areoriented at an angle A of approximately 45 with respect to the row axes,to provide a considerable width of stringing window along both thecolumn and row axes. If each column axis 24 were at 90 to each row axis20, then the stringing windows would be the same in both directions, andboth stringing windows would be small. However, by angling the columnaxis 24 at an angle B of at least a few degrees away from theperpendicular, a greatly increased column stringing window is obtained.

An understanding of the magnitude of the advantage gained by utilizingcolumn axes oriented at less than 90from the row axes, can be gained byconsidering the increase in the stringing window, for a typical kind ofcore array. FIG. 5 illustrates a portion of an array utilizing cores16a, 16b, 16c which are of the typical smaller size which has an outerdiameter D, of 14.5 mils (thousandths of an inch), an inner or holediameter D, of 8 mils, and a thickness T of 4 mils. The angle A of thecore orientation with respect to the row axis 20 is 46. For a prior arttypical array wherein an angle A of 45 is utilized, the width W, of therow stringing window is slightly less than 3 mils. As a result,difficulty may be experienced in projecting a needle of 3 mils diameterthrough the row of cores when stringing the row wires. By increasing theangle A to 46, a stringing window width of slightly more than 3 mils isobtained, which facilitates the projection of a standard 3 mil needlethrough the rows of cores.

In a prior art array, a core adjacent to core 16a in the same column,would be at the position 16b wherein the center b of one core wasdirectly under the center 30a of the other core, so that the column axisat 24: would be at 90 to the row axis 20. As a result, the width W, ofthe column stringing window would be less than 3 mils, so that thestringing of column wires could not be managed, especially if the rowwires had been already strung. However, by utilizing column axes atangles of less than 90, alarger column stringing window is obtained,which not only facilitates the stringing of the column wires, but whichpermits multiple large diameter wires to be utilized along the columnaxes.

One choice of column axis 24w employs an angle of 77 from the row axis20. For this angle, the center of the adjacent core 16b is moved fromthe position 30b to the position 30w. This direction of core movement isrequired because it insures that the adjacent core 16c of the same rowas core 16b will remain clear of the core 16a, the direction of movementbeing along the axis of the hole of the core 16b. With the core 16bmoved so its center is at the position 30w, a large increase in thecolumn stringing width is obtained, the stringing window increasing fromabout 2.8 mils to 4.7 mils, or in other words increasing by about 70%.This much larger stringing window facilitates the stringing of columnwires through cores which have already been strung with row wires, andalso permits the use of larger gauge wires along the column direction.

The movement of the center of core 16b from the position 30b involves anincrease in the vertical spacing S, of the cores in a directionperpendicular to the row axis 20. However, a substantial verticalspacing isnecessary to keep the row stringing windows clear ofinterference from the cores lying in adjacent rows. For example, if thecore 16b is positioned with its center at 30b, row wires cannot bestrung through the core 16b v because of interference from the bottom ofthe core 16a. A downward movement, to at least the position 30w, isrequired to eliminate such interference with row stringing. Thus, anangle of approximately 77 really does not add to the required verticalspacing of the cores, and yet it results in a greatly increased width ofcolumn stringing window. A further slight decrease in the angle C of thecolumn axis to about 70, at the orito 5.6 mil, or in other words about20%. The vertical spacing S undergoes an increasefrom about 8.5 mils to10.1 mils or about 20%. A still further decrease below 70, in the angleC of the column axis with respect to the row axis, is normally notdesirable. A further decrease to 65 as indicated by the line 242,results in an increase of the column stringing window to 6.2 mils, or inother words about 30% as compared to the stringing window at 77.However, the vertical spacing increases to about 12.1 mils or about 40%as compared to the angle of 77. An angle between 77 and 90 can beutilized, although there is no advantage to that in the case of thecores of the dimensions shown in FIG. 5. At an angle C of 85, asrepresented by the line 24a, the column stringing window is about 3.6mils, which is about halfway between the stringing window width obtainedfor 90' and 77.

The use of column axes angled at less than 90 to the row axes results inan increase in the size of the entire array, where the array is mountedon a rectangular substrate, as shown in FIG. 4. This is because theangling of less than 90 results in a horizontal shift between theuppermost and lowermost row of cores. However, the amount of increase isgenerally not prohibitive, and it is often possible to utilize the areasat 40 and 42, which are not occupied by cores, to hold other componentswhich must be'mounted on the substrate.

Magnetic cores are produced in a variety of sizes, although the mostcommon sizes commercially used in magnetic core arrays normally rangefrom about 14 mils to about 30 mils in outside diameter. The most commontype of binary core has relative dimensions of the type illustrated forthe core of FIG. 5, with an outer diameter D, of about 14 times a unitlength, and an inside diameter D, about eight times the unit length, anda thickness T about four times the unit length, the unit length used inthe example described earlier herein being 1 mil. Thus, for a core ofabout 30 mil outside diameter, a typical inside diameter is about 16mils and a typical thickness is about 8 mils. Cores have been recentlydeveloped which can be utilized in more than two different states, andthese multi-state cores have a somewhat greater thickness in relation totheir outside and inside diameters than the cores of FIG. 5. Theincreased thickness of such cores results in a smaller stringing windowfor a given orientation of the cores. However, by skewing the array sothat the orientation of the column axes are at less than 90 to the rowaxes, a great increase in the column stringing window is obtained.

FIG. 3 illustrates cores 50a,- 50b which have a thick ness dimension Tabout 50% greater than for the cores of FIG. 5, in relation to theinside and outside diameters. Thus, for a 30 mil outside diameter and 16mil inside diameter core, the thickness T,,, is about 12 mils instead of8 mils. The stringing window is about 2.8

entation of line 24y, can be utilized to obtain a moderate increase inthe column stringing window at the cost of a moderate increase in thevertical spacing. With the center of the core 16b moved from theposition 30w to 30y, the stringing window increases .from about 4.7 milmils along a column axis 52 at an angle C of 90 from the row axes 54.For such a core, a substantial increase in the stringing window alongboth the row and column axes may be required. This can be achieved byincreasing the core orientation angle A from 45 to 50, to increase therow stringing window to about 4.4 mils, and by decreasing the columnangle from 90 to about to obtain an 8 mil column stringing window forthis core orientation.

Thus, the invention provides an arrangement for an array of magneticcores, which facilitates the stringing of wires through the cores andwhich enables the use of larger diameter wires. This is accomplished byorienting the columns of the array of less than 90 to the axes of therows. For a typical binary core, a column axis at about 77 (i.e.,between 75 and 80) with respect to the row axis provides a maximumincrease in column stringing window width, with little if any increasein required vertical spacing of the cores. A rotation of the column axesaway from the 90 or perpendicular direction should be at least a fewdegrees. A ro-- tation of more than about (to an angle C of 70) isnormally not necessary where the core is oriented at about 45 from therow axis. A rotation of the column axes through much less than 70normally is not useful because the cores then interfere greatly with oneanother unless the spacing of the cores is greatly increased. A largerincrease in the spacing of the coreswill defeat the major purpose of therotation, which is to obtain a large stringing window while maintaininga small size of core array. The theoretical lower limit of the angle Cis 45, at which the stringing-window is a maximum and equal to thediameter of the hole in the core, but in which the required spacing ofthe cores increases without limit. Of course, the cores can be orientedin the manner shown in FIG. 6, in which case the angle C is taken asillustrated in that Figure between the axes 50 and 52.

Although particular embodiments of the invention have been described andillustrated herein, it is recognized that modifications and variationsmay readily occur to those skilled in the art and consequently it isintended that the claims be interpreted to cover such a plurality ofmagnetic cores arranged in substantially straight rows and columns onthe support, with the axes of the columns oriented at an angle less than90 and more than 45 to the axes of the rows, each core having a hole andeach core oriented with the axis of its hole angled at least severaldegrees from both the column axis and from the row axis on which thecore lies; and

a plurality of wires extending through the cores along the axes of therows and along the axes of the columns.

2. A magnetic core memory comprising:

a support;

a plurality of magnetic cores arranged in substantially straight rowsand columns on the support, with the axes of the columns oriented at anangle of between 70 and 85 to the axes of the rows; and

a plurality of wires extending through the cores along the axes of therows and along the axes of the columns.

,3. In a magnetic core memory which includes ringshaped cores arrangedin substantially straight rows and columns on a support, and in whichwires are strung through the cores along the axes of the rows andcolumns, and in which each core has an outer diameter of approximately14 units, a hole diameter of approximately 8 units, and a thickness ofapproximately 4 units, wherein said unit is a linear dimension fixed forthe array, the improvement wherein:

the axes of the columns are oriented at 'an angle B with respect to theaxes of the rows, where B is between 70 and 85, whereby to greatlyincrease the stringing window while minimizing the increase in the sizeof the array. 7

4. In a magnetic core memory which includes ringshaped cores arranged insubstantially straight rows and columns on a support with the coresangled approximately from the row axes, and in which wires are strungthrough the cores along the axes of the rows andcolumns, and in whicheach core has an outer diameter of approximately 14 units, a holediameter of approximately 8 units, and a thickness of approximately 4units, wherein said unit is a linear dimension fixed for the array, theimprovement wherein:

the axes of the columns are oriented at an angle of 77 with respect tothe axes of the rows.

1. A magnetic core memory comprising: a support; a plurality of magneticcores arranged in substantially straight rows and columns on thesupport, with the axes of the columns oriented at an angle less than 90*and more than 45* to the axes of the rows, each core having a hole andeach core oriented with the axis of its hole angled at least severaldegrees from both the column axis and from the row axis on which thecore lies; and a plurality of wires extending through the cores alongthe axes of the rows and along the axes of the columns.
 2. A magneticcore memory comprising: a support; a plurality of magnetic coresarranged in substantially straight rows and columns on the support, withthe axes of the columns oriented at an angle of between 70* and 85* tothe axes of the rows; and a plurality of wires extending through thecores along the axes of the rows and along the axes of the columns. 3.In a magnetic core memory which includes ring-shaped cores arranged insubstantially straight rows and columns on a support, and in which wiresare strung through the cores along the axes of the rows and columns, andin which each core has an outer diameter of approximately 14 units, ahole diameter of approximately 8 units, and a thickness of approximately4 units, wherein said unit is a linear dimension fixed for the array,the improvement wherein: the axes of the columns are oriented at anangle B with respect to the axes of the rows, where B is between 70* and85*, whereby to greatly increase the stringing window while minimizingthe increase in the size of the array.
 4. In a magnetic core memorywhich includes ring-shaped cores arranged in substantially straight rowsand columns on a support with the cores angled approximately 45* fromthe row axes, and in which wires are strung through the cores along theaxes of the rows and columns, and in which each core has an outerdiameter of approximately 14 units, a hole diameter of approximately 8units, and a thickness of approximately 4 units, wherein said unit is alinear dimension fixed for the array, the improvement wherein: the axesof the columns are oriented at an angle of 77* with respect to the axesof the rows.